Various and sundry techniques have been utilized heretofore by surgeons in performing sternal splitting incisions on a patient to permit operative access to internal organs within the chest cavity, and particularly to approach the auterior, superior or posterior mediastinum for removal of lesions of the thymus, explorations for parathyroid adenoma, and approaching the heart for modern open heart procedures. After making a sternal incision, either median or transverse the rib cage can then be separated to provide the necessary access. In making the cut, the surgeon has historically been forced to utilize his own judgment as to the depth of the cut, attempting to avoid contact with any internal organs or great vessels that could be adversely affected by severance. As such, blades rotary in nature and reciprocatory or oscillatory in nature have been utilized with power operated surgical saws. In addition, and as a primary tool, due to the safety hazards involved, surgeons have utilized a manual blade such as the Lebiske knife which, after incision at a point just above the sternum, can be inserted with a curved tip of the blade resting beneath and against the sternum. While lifting the curved blade to attempt to raise the rib cage off internal body organs, the surgeon can strike a surface of the blade with a further tool to drive the blade through the sternum and open the chest cavity.
Obviously, all the techniques described above are fraught with problems and danger to the patient. For example, incident to use of the normal rotary or oscillatory blades of the prior art which do not possess guard elements, the surgeon must very carefully use same to avoid a downward surge into the mediastinum once the sternum has been completely severed. Such practices must be very tediously followed since the marrow cavity varies with the age and size of the patient. Likewise the size of the individual, physical abnormalities and the like may vary location of the internal body organs. The adult sternum measures between 1 centimeter and 2.5 centimeters with an average depth from the outer table through the marrow cavity and inner table approximating 1.5 centimeters. With infants or small children the operative procedures become still more delicate than with adults due to location of the internal body organs and the ever present danger of reaching same with a power saw. Utilizing manual techniques, a greater stress is obviously placed on the surgeon during the actual operation procedures. Likewise, since the curved tip Lebiske knife is utilized and must be physically driven through the bone, the actual cut is not nearly as neat as when accomplished by a rotary or oscillatory blade, the patient suffers greater possible trauma and likewise there is an ever present danger of causing further damage to the rib cage due to the possibility of fracture of adjacent bones prompted by forces applied to the knife.
Surgical saw blades of the present invention minimize, if not alleviate, the problems set forth above, in that the blades may now be provided with a guard means extending outwardly from at least one side thereof, the particular location of which defines the precise depth of cut that is permitted. The need for manual procedures is thus normally eliminated and the rotary or reciprocatory surgical saw blades may be utilized with a much higher degree of precision whereby the possibility of damage to internal body organs and great vessels is substantially lessened. Blades of the present invention are particularly useful on patients undergoing secondary open heart surgery since the auterior mediastinum of the patient can be markedly reduced in size as a result of the previous surgery, making the heart and great vessels more vulnerable to injury.